Heterogeneous catalysts are typically provided as particulate beds through which a liquid and/or gaseous reactant mixture is passed, often at elevated temperature and pressure. Therefore heterogeneous catalytic materials are often provided in shaped form to provide a balance of catalytic activity and throughput. In general smaller catalyst particles have a higher surface area and therefore activity, but provide lower throughput because the pressure drop through the catalyst bed is higher. To counter this, various catalyst designs have been used, which may have one or more flutes or channels running along the exterior surface in an attempt to increase the geometric surface area while minimise pressure drop.
U.S. Pat. No. 4,328,130 discloses a shaped catalyst in the form of a cylinder with a plurality of longitudinal channels extending radially from the circumference of the cylinder and defining protrusions therebetween, wherein the protrusions have a maximum width greater than the maximum width of the channels. The catalysts depicted have 2, 3 or 4 truncated-V shaped channels.
WO 2004/014549 discloses shaped heterogeneous catalysts for gaseous reactions, comprising a cylindrical unit having a diameter to height ratio in the range between about 0.5:1 to 1:1 and having a plurality of shaped holes of non-circular cross-section therethrough. Some embodiments additionally have two, three or four V-shaped flutes or channels running along the external length of the cylinder.